Re: [PATCH v3] mm/usercopy: get rid of CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

[Linus Torvalds]

On Tue, Aug 30, 2016 at 6:04 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> There are three usercopy warnings which are currently being silenced for
> gcc 4.6 and newer:

[.. snip snip ..]

Ok, I'm not entirely happy with the timing, but I think the problem
counts as a regression since it effectively made all the checks go
away in practice for most people, so I'm going to apply this patch.

I know Al Viro is working on some uaccess cleanups and trying to make
a lot of this be generic, so there's hopefully cleanups coming in the
not too distant future (I say "hopefully", because I worry that
looking at the mess will make Al dig his eyes out), but this seems to
be a clear improvement.

I still do wish we'd move the x86 __builtin_constant_p(n) check
around, so that x86 wouldn't do the run-time check_object_size() for
the trivially statically correct case, but I guess that's a separate
issue from this patch anyway.

If somebody has objections to this patch, holler quickly, because it's
about to get applied. 3.. 2.. 1..

                         Linus